1. Field of Invention
This invention relates to a navigation system that searches a route according to an input of a point as a destination and executes route guidance along the searched route.
2. Description of Related Art
Generally, there are navigation systems that display arrows indicating "straight", "turn right" and "turn left", etc., on a display screen, and perform guidance by audibly outputting the contents thereof when a vehicle comes close to an intersection, etc., during the route. If a road has a plurality of lanes, the driver needs to change lanes in advance before making a right or a left turn at an intersection, so the arrows draw his attention prior to the intersection so that he can change lanes.
In Japanese Laid Open Patent Application No. S62-93617A, direction arrows for respective lanes are displayed as lane information (the same one as applied to the actual road) when the vehicle only reaches a predetermined distance before the guidance intersection. Further, in the Japanese Patent Laid Open Patent Application No. H5-92636A, arrows indicating a right or a left turn are displayed, the phrase "Travel on right lane" or "Travel on left lane" is displayed, and "come near to the right" or "come near to the left" is audibly output when the vehicle reaches a predetermined distance before an intersection at which the vehicle must turn.
However, in a method according to the Japanese Laid Open Patent Application No. S62-93617A, since the same display method is always applied even to the passing intersection and guidance intersection, it holds a problem that the driver can not distinguish between lane display guidance of the passing intersection and lane display guidance of the guidance intersection which is more important than the passing intersection. In either of the above methods, since lane information is displayed when the vehicle reaches a predetermined distance, for example 200 m, before the guidance intersection, if the passing intersection exists on a road that includes many traffic lanes at the guidance intersection, it brings a result that the vehicle changes lanes for a left or right turn only lane before the passing intersection. It further brings a result that the driver feels the stress due to the uneasiness about the lane change if the number of lanes increases or decreases between the vehicle present position, the passing intersection and the guidance intersection.